Telephone-exchange system



March 8, 1927. 1,620,012

B. G. DUNHAM ET AL TELEPHONE EXCHANGE SYSTEM.

Filed Sept. 17, 1926 8 Sheets-Sheet l March s, 1927,

B. G. DUNHAM ET Al,

TELEPHONE EXCHANGE SYSTEM 8 Sheets-Sheet' 2 www T w @NN i qm ffiesA y r l 1 62o, 12 Mach g M26!" B. s. DUNHAM ET AAL o TELEPHONE EXCHANGE SYSTEM Filed sept. 1v, 192e s shawls-sheet s `March 1927;

8 B. G. DUN-HAM E1- AL TELEPHONE EXCHANGE SYSTEM Filed Sept. 1'?, 1926 8 Sheets-Shet 5 March 8, 1927.

B.G. DUNHAM ET ,AL

TELEPHONE EXCHANGE SYSTEM Filed Sept. 1'?, 1926 8 Sheets-Sheet' 6 Marginal March 8, 1927;

1,620,012 B. G. D'UNHAM ET AL TELEPrgoNE EXCHANGE SYSTEM Filed Sept. ,17, 1926 8 Sheets-Sheet '7 'by l LLM/179;

March 8,1927.

1,620,012 B. G. DUNHAM ET AL,

TELEPHONE EXCHANGE SYSTEM Filed Sept. 1'?, 1926 8 Sheets-Sheet 8 Hh y M. www;

, trunk finder and Patented Mar. 8, 1927.

BERT G. DUNHAM, 0F HA'WTHORNE, AND TVILLAM T.

. MIE..

HANES, OF MOUNTAN LAKES,

garni NEW JERSEY; SAID HAINES ASSIGNOR TO AMERICAN TELEPHONE AND TELE- -GRAPH COMPANY, A CORPORATION OF NEVI YORK, AND SAE) DUNHAM ASSIGNGR TO WESTERN ELECTRC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A COR- PORATION 0F NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Application led September 17, 1926. Serial No. 136,033.

rlhis invention relates to telephone eX- cliange systems and more particularly to the establishment of connections between subscribers lines in manual and machine switching offices.

ln accordance with the present invention the interconnection of manual and machine switching offices is accomplished by trunks which appear at a manual operators position and which when selected for use by that operator are automatically associated with an incoming operators position at the machine switching office. The incoming operators equipment is also automatically associated with a control device which may be set by such equipment to operate a train of switches connecting with the called sub scribers line and to connect such train when set with the trunk. According to another aspect of the invention, an erroneous partial setting of the control device may be cori'ected by the machine switching operator. According to an additional aspect of the in vention the disconnection of the trunk by the manual operator prior to connection with the train of switches will also cause the re-y lease of the control apparatus and the train of switches.

The operation of a telephone system embodying the invention is briefly as follows: lli/*hen a subscriber in a manual office wishes to converse with a subscriber in a machine switching otiice, he will communicate the number to his operator in the usual manner. The Yoperator will then insert the calling plug of her cord circuit in the jack of Aan idle trunk leading to the machine switching oi'iice. The trunk circuit at the auto matic otlice will function to close a start circuit for a link which includes a trunk finder, a position finder and a sender finder. rI he the position finder will be operated simultaneously to connect the trunk with an idle operator at the machine switching` oiiice. llVhen an idle position and the trunk have both been found a talking circuit is completed between the two operators, and a momentary tone is connected thereto to inform the manual operator that she may give the wanted number. As soon as the position is found the sender selector is operated to find an idle sender and establish control circuits between the sender and the machine switching operators keyboard and between the sender and the first w of the first selector and subsequent selectors to select the called line as soon as the second digit is registered. When the last digit h as been recorded an indication is'transmitted to the link to dismiss the position. llhen selections have been completed the link dismisses the sender, causes the connection of the trunk to the train of switches and the release of the trunk ndei.

rlhe machine switching operator is provided wit-h a key which permits cancelling` a partial registration withouty disconnecting the position and sender. rEhe completion of the established connection is under the control of the manual operator and may be prevented by disconnection by that operator at any point.

A clearer understanding of the invention may be obtained froml the following detailed description and the attached drawings, in which: p A

Fig. l shows diagrammatically a. calling subscribers substation connected to an answering jack, and a cord circuit at an A operators position in a manual ofiice, and further shows in detail -an outgoing trunk jack associated with a trunk circuit in the called office, also a first selector of the called oiiice enclosed by the broken line.

Figs. 2, t and 5 show the link circuit comprising a trunk finder circuit 2), a position selector (Fig. 5), and a sender selector (Fig. 4L).

Fig. 3 shows a position circuit for a cordless B operator to enable such operator to talk with the manual A operator over a connection established through the link circuit, and to set thev selected sender by 'means of a keyboard sender.

the B opera- 'of relay 200,` right shows the proper relative arrangement oit Figs. 1 to 8.

Detailed descripione-Finding the tru-nk.

position in the Well known manner, Whereupon the A operator inserts plug 102 inte the answering jack 101 and receives the number ot' the Wanted subscriber. The A operator by means ot her cord circuit 103 nowA connects with an idle trunk outgoing to the Wanted oliice by inserting the calling plug 112 into an outgoingtrunk jaclr` .such as 'jack Jack 104 is `connected by means oftrunk conductors 105 and106 with the called office, and When the manual operator inserts Vplug112injacl` 104 relay 10T operates over the trunk loop in va circuit which may be traced from ground through the right Winding-,of relay 107right back contact of relay 100,v right normal Contact of relay 110, upper lett Winding et' repeating coil 111 to the tip ot jack 104, tip ot plug 112, through the usuall polarized relay (not shown) of the cord circuit 103, ring ot plug 112 and jack 104, conductor 106, through the lower lett Winding ot repeating coil 111, lett norma-l contact of relay 110, lett back contact of relay 109, lett Winding of relay 107 to battery. The operation ot relay 107 in turn operates relay 108 in an obvious' circuit.

The operation of relay 1,08 closes the eircuit for starting the trunk finder by connectingground to ,group start lead 113. Relay 200 operates in a circuit which may be traced from ground' at the right back contact of relay 114, outer right front contact ot relay 108, conductor 113, through nermally closed group start lrey 201,;l Winding back Contact of relay 218 to battery. Relay 200 operated `connects ground to commutator segment 115 corresponding to the level in Whichthe trunk appears before trunk finder 250. (The apparatus Within the dotted rectangle of Fig. 2 is common to a plurality ot trunk. circuits appearingjn the same level.) Relay 202 non7 operates in a circuit which may be traced from battery inthe alarm circuit, right Winding of relay 202,4 middle lett baclr contact ot relay 210, middle right back contact of relay 442, intermediate Vnormal contact of key 240, to ground at the right contact ot relay 200. Y

Relay 202 operated closes anoperating path for relay 203 which may be traced troni battery, right Winding of relay 2,03, armature and closed contact of rotary magnet 208, closedicontactand armature of vertical magnet 206, conductor 228, Contact of relay 202 to grounded contact otrelay/,74210.y Relay 202 operated also closes a start lead to the position tinder at its middle trent contact, and opens a short circuit between conductors 204 and 205 at its outermost lett back contact. Relay 203 operated energizes theyertical'magnet 206 i cult which may be traced from battery through the y* idinov el vertical magnet 206, lett baci; co et or relay 207 to groundef contact oit relay 203. Vertical magnet 206 operates, thus brealring the energizing path for relay 203. R- layl203 will ,accordingly release and allow Vertical magnet 206 to release as Well, cans ing the trunk linder switch to take one yer-V tical step.V lflagnet 206 haring released, rf lay203 will energize and the trunk finder switch will Vtaire another ,al s en. This action will continue until gA tator brush 116 e, ges grot. l. d nent 115. RelayV 203 will be held operated and relay 20TWill'operate in a circuit which i f be traced fronrbattery through the e J Winding of relay 203, contact et rotary man`- net 208, conductor 209, lett Winding of relay 207, nent to the innermost lett back coin tact of relay 210condu`ctor 230, commutator brush 116 eommutator segment 115, conductor 231 to ground kat the lett trent contact of relay 200. The operation,o1e relay 20,7 opens the energizing circuit ot y iical magnet 206 and closes circuit for rotary magnet 208 which may be traced fromv battery through the Winding of magnet 208, conductorv 232, lett trent contact et relay 20?' to grounded contact et' relay 203. Rotary magnet 208 and' relay 203 function the same as in the case oit'yertical stepping mag net 2,046' and the switchA Willtalre rotary steps until the transfer Aconductor 211 is connected to contact 11,8. This Contact is connected te battery through relay 100 et the trunk circuit, and rele-37.1203 Will be held energized in a circuit lwhich may be traced trom ground through the lett rinding oit relay 210, through the lett Winding et relay 203 in series, outer front contact ol relay 202, conductor 211, brush 235, contact 11,8, test conductor 11'?, lett back contact ot' relay 114, lettlcontact of relay 108, Winding et relay109 to battery. Relayv Will energize in this circuit and loclr to ground through the ott'fnormal contact 212 over its middle lett front conta'ctbut relay 109 does not operate in series with relay 210. The operation ot relay 210 connects direct ground from the innermost grounded armature et that relay to test conductor 211, operating relay 109, and opens the energizing circuit of relay 20',7 at its innermost back contact. Relay 207 releases and extends the start circuit` to the next idle trunk finder.

y *Thisl extended start circuit may be traced from ground at the right contact o1- relay 200, intermediate normal Contact of key 240, middle right back contact et relay 442, middle lett trent contact of relay 210, right back lll) ot relay 431 to ground.

contact ot relay 207, inner right back contact oit' relay 442, upper normal contact of key 240 thence to the out start wire con nccted to this contact of key 240.

Relay 210 operated closes a. lcircuit Jfor operating relay 213 which may be traced from battery through the winding of relay 213, innermost front contact of relay 202 to the intermediate grounded armature oit relay 210. The operation of relay 210 also opens the comniutator brush circuit traced hereinabove and closes a chain relay circuit at its lett front innermost contact and armature which vforms a part ot an all-findersbusy circuit. The operation of relay 213 at this time connects the talking leads of the trunk through to the link, closes the pulsing leads oyer which the switches are to be operated in reaching the wanted number, opens the release magnet circuit and partially closes a short circuitiiig` path across leads 204, 205 at its lowermost iront contact.

The operation of relay scribed causes the release of relays 107 and 103. Relay 109 operated, locks to test lead 117 in a circuit which may be traced from battery, winding ot relay 109, left iront contact of relay 109, conductor 120, leift back contact of relay 114 to ground on test lead 117.

Finding a position.

As soon as the trunk finder switch took one step, relay 400 operated in a circuit which may be traced from battery, winding ot relay 400, conductor 402, ofi-normal contact 229 to ground at next to the outermost lett back contact of relayv 210. The operation o t relay 400 causes relay 401 to operate in an obvious circuit.

"When relay 213 operates as above described, extending the talking conductors through to the link circuit, relay 431 operates in a circuit-from battery, lett winding ot relay 431, outer lett back Contact of relay 439, lett normal contact ot relay 437, conductor 205, innermost upper contact ot relay 213 through the trunk finder, conductor 100, ring of i ack 104 and plug 112, through the usual polarized relay (not shown). ot the A operators cord circuit, tip ot plug 112 and jack 104, conductor 105, through the trunk finder, next to the innermost upper contact ot relay 213, conductor 204. right normal contact ot relay 437, right winding The operation of relay 210 opened the energizing circuit of relay 400, but relay 400, being slow-to-release. remains energized long enough for relay 431 to operate and close alocking circuit Jfor relay 400 over its lett front contact to Iground at the front contact of relay 400. Relay 400 holds relay 401 operated. Since the operation ot relay 401 is necessary to close switch setting conductor 233, as will 109 as aboye de-' be described hereinafter, the extension ot the connection is now inpart under the control of the A operator.

vWhen relay 202 operated to start the trunk iinder, relay 403 operated in a circuit which may be traced from battery., through winding of relay 403, conductor 235, iront contact and grounded armature ot relay 202, closing the position finder start circuit. The operation ot relay 403 closes a circuit ttor relay 500 which may be traced from battery, winding of relay 500, conductor 532, noi-mal contact of relay 529, conductor 533, right back contact of relay 520, outer lett back contact of relay 503,'conductor 534, lett iniddle contact ot relay 403, conductor 352 to ground-in any idle position circuit to which the position iiiider has access. Relay 500 on operating connects ground trom its right contact to the winding oi relay 501 which thereby energizes. Relay 501 operated closes an energizing circuit for operating stepping magnet 502 ot the position iinder which may be traced from grounded battery, winding ot stepping magnet 502, conductor 530,1nor

mal contact or relay 503, conductor 537, contact of magnet 404, conductor 538, contact ot stepping magnet 502, winding of relay 503, inner' right contact ot relay 501, conductor 539 to ground at the inner left contact of relay 403. Relay 501 operated, thus closes a path 'for operating relay 503 and prepares a locking path tor relay 504 over its left front contact to ground at the back contact of relay 505. li' the terminal on which the test brush 527 ot the position finder. is resting is grounded, indicating` that the position is busy or vacant as will be dcscribed hereinafter, a. shunt is clos-ed around the winding oi' relay 503 extending over the outer right contact ot relay 501, lett back contact of relay 503, inner right back contact ot relay 509, brush 527, to grounded conductor 507. rllhe stepping magnet 502 will operate its armature and interrupt its own circuit causing the switch brushes to advance one step. This action will continue until an idle terminal is tto-und. V hen an idle terminal is found, relay 503 will operate from battery through the stepping magnet in the circuit hereinabove traced, preparing a circuit from ground at the back contact ot relay 504, winding oit relay 505, outer right diront contact of relay 503, outer right back contact of relay 510, brush 556 to conductor 500. Relay 503 operated, also grounds test conductor 507 and closes a path for operating relay 504. ii'i there is only one switch engaging the multiple terminals ot the position at this time, relay 505 will operate in the l circuit traced from the battery connected to conductor 506 oyer the back contact of relay 305 and open the. path tor operating` relay 504. It two position finders test the terminals ot a position at the saine time, neither lim relay 505 Will operate and the V position iinders Will continue to' operate until' they test different positions, when each relay 505 Will operate. Relay operated, operates relay 508 in a circuit which may be traced from battery, Winding of relay 508, right outer back contact of relay 500, conductor 540, front Contact ofrelay 505 to ground. The opera ion of relay 508 opens the enerf gizing' circuit for relay 500 which Will restore to normal, causing to release, thusopenin; the energizingcircuit for relay 505. The dcen'ergizatidn of relay7 505 opens the circuit for energizing relay 508. Under this condition, relay 508 Will lock over its left middle contact, the Winding of relay 509, conductor 539 to ground at the innermost left Contact of relay 403, Relay 509 is energized in this circuit and Will .in turn Operate relay 510 in a circuit which may he traced from batte'iy, Winding of relay 510 oyer the left front contact of relay 509. conductor 541; right back contact of relay 405, outer left back contact of relay 406, conductor 407 middle contact of relay 401, inner right Contact of relay 403, conductor 237 to the middle Qroundedarmature or relay 210. Relay 508 operated, connects guarding `ground to test brush 527 of the position finder in a Circuit iyhich may be traced from ground, right middle 'Contact of rela-y 403. conductors 412 andA 408; right back contact of relay 542, conductor 409, rig-htback contat of relay 406, conductor 543, inner left front cnta'ct of relay 508 to test brush 527f Relay 508 operated, connects; over its refht front Contact, stepping magnet 404 of the sender selector to .the re lays which control the operation thereof. Relay 509 operated, transfers the lead 540 to relay 511 and connects the test brush 414 through to the relays iyhich control the operation of the sender selector. Relay 510 operated. transfers the test circuit from lead 506 of the position selector to lead 419 of the sender selector oyer vits outer right front contact. It also closes the talking leads 514 and 515 to the B operators position (Fin.

relays 501 and 503 3) and closes the start lead 416 to relay 500.

Finding a sender.

This start circuit for relay 500 may be traced from battery through the nrindinn` of relay 500. right normal contact of relay 529, inner right front contact of relay 510, right back contact of relay 511, 'conductor 416, through the right Contact of key 805;.to ground at the left back contact of relay 802 of anyidle sender inthe grroup.y As before, relay 501 closes the circuit for the sender selector magnet 404:

The circuit of the sender selector stepping magnet 404 may be traced from battery through the VWinding of tlie magnet, right alternate contact of rela-y 508, back contact of magnet 404,' back contact of magnet 502, and thence in' parallelthrough the Winding or" relay 503 to grounded conductor 539 and oyer the outer right front contact of relay 50]., left back contacto'f relay 503, 4inner ria'htfront eontact of relay 509, to conductor 417,` brush 414,' conductor 415, left contact of key 805, to the front, contact of relay 807 which Will be operated ifthe sender is busy. In the case ofa busy sender, therefore, relay 503 is shunted as in the 'case of a busy position and magnet 404 operates, opening` its own circuit and advancing' the sender .scle'ctor to the next sender. When ,an idle sender is found relay, 807 will not be operatec .and no shunt will be closed around the Winding' of relay 503. Relay 503 in 4operating connects ground over its inner left front contact; to brush 414 to mark the sender busy to `other sender selectors. A

Relay 50rwill also close a circuit from ground at the back contact of relay 504 through the' Winding' of relay 505, outer right front Contact of relay 503outer left front contact of relay 510, in n'er right normal con tact of relay 517, conductor 419, brush 427. conductor 418,- right back contact of relay 802, resistance 880 to battery. Relay 505 operates in this circuitand closes a circuit from battery .through the Winding of relay 511, outer right front Contact of relay 509 to ground, `at the front contact of relay 505. Relay 511 operates, connects ground to test conductor 417 and fcloses, a locking 'circuit for itselfV over its outer left contact, Winding of relay 517 to grounded conductor 408. As beforeA the operation of relay 503 closed a cir` 'cuit for slow-tooperate relay 504 which when it opera-tes opens the circuit of relay 505, Wliiclrwhen it operates in turn opens the circuit for relay 504. rlhe operation of relay 511 a's previously described opens the circuit of relay 500, restoring` that ,relay and relays 501 and 503 to normal. Therelease of relay 505 when its circuit is opened by relay 504, opens the energizing circuit of relay 511 permitting relay 517 to operate in the locking circuit of relay 511: Relay 511 operated also opens the start circuit from relay. 500.l

Relay 410 noiv operates in a circuit which may be traced from battery through Winding of relay 410;y conductor 411, outermost left armature and front Contact of relay 517, conductors 545, 408 andv412, right middle front contact of relay 403 to ground. An additional locking' circuit for relays 511 and 517 in series is now closed.. which circuit may be traced from battery, through Winding of relay 511, outer-,leftfront contact of relay 511` conductor 544, Winding' of relay l517, outer left front Contact of relay 517, conductor 411, left front contact of relay 410, conductors 413, 408 and 412 to ground at the middle ground through brush 527 to conductor right front contact of relay 403. Relay 517 operated connects conductors 521, 506 and 522 from the position finder to the corresponding conductors 419, 420 and 461 troni the sender selector. Relay 410 operated connects the pulsing leads 2f 3 and 234 trointhe trunk finder (Fig. 2) to the sender selector pulsing leads 422 and 421. Relay 410 operated, also locks to the vcontrol ground supplied by relay 403.

Operatcn. of position circuits.

I preparing a start circuit for the operation of the position equipment. lt also connects ground over its right iront Contact, right back contact of relay 301 to conductor'352 tor indicating to the position finder that an idle position .is available.

llllien now the position finder connects with the position the battery connected to conductor 507 permits relay 503 to operate, and when relay 503 operates, connecting 507, the circuit ot' relay 314 is completed and that relay operates. Relay 314, in operating, supplies ground to the numerical keys and other parts ot the circuit 'or controlling the position apparatus. lt also closes an obvious circuit tor operating relay 354. Vhen relay 510 operates to initiate the operation of the sender selector, relay 300 will operate in a circuit which may be traced from ground at the outer lett bach contact of relay 549, conductor 550, left Winding ot relay 542, middle lett liront. contact ot relay 510, position finder brush and contact 551, conductors 515 and 310 through the Winding of relay 300, conductors 31 and 514 to the Contact and brush ot the position iinder, outermost lett trent contact ot relay 510, right Winding of relay 542 to battery. Relay 300 operates audin 'turn operates relay 301 in a circuit which may be traced from battery through the Winding ot relay 301to ground at the right il'ront contact of relay 300.

lith relays 301 and 354 operated, lamps 302 and 303 are lighted, lamp 302 over the inner right front contact ot' relay 354 and the outer left front contact oi' relay 301 to ground; lamp 303 over the right back contact ot relay 319 and the lett back contact of relay 306 to ground at the outer right contact oi"- relay 354. vThe lighting of these for relay 353 extending through the Winding of that relay, left front contact ot relay 354, outer right front contact of relay 301 to ground at the right contact of relay 350.`

The operation 314 from the test lead 507 but relay 314 is held operated by ground over the inner lett contact ot relay 301. Relay 353 connects ground over its outer right l'ront contact to test lead 507 to mark the position busy. lt also closes a locking circuit for itself to ground over its middle right contact. At its inner left contact relay 353 connects ground through the Winding of relay 355 to battery at the lett normal contact of relay 356. Position circuits of this type are arranged to transmit tWo short impulses ot' tone, usually called Zip tone, to the A operator to notify her When the B operator is ready to receive the number. The first tone is transmitted as soon as relay 301 operates due to the closure of a circuit from ground, through the secondary Winding of tone coil 365, over the inner right front contact of relay right ing ot'repeating coil 359 to ground. This induces a to-ne in the upper Winding of rem peating coil 350 which is transmitted overv the bach contact of relay 356 to conductors 514 and 515, brushes 552 and 551, le'ft front contacts of relay 510, condenser 563, conductor 205, loWerinost contacts of relay 213, through the trunk iinder, conductors 106 and 105, jack 104 and plug 112 to the A operators telephone which .she main# tains connected to the cord circuit by the usual listening hey (not shown). ylhe operation of relay 355 in the circuit trac-ed above, closes a locking` circuit for that relay from battery over its right alternate contact and also closes a circuit from battery over the normal contact ci relay 356, left back contact of relay 357 Winding ot relay 358 to ground at the lett contact of: relay 355. A s soon as relay 35S operates it opens the tone circuit and the tone ceases in the A operators headset. lt also closes a circuit from battery over its right alternate contact through the Winding of relay 357 to ground at the left contact of relay 355. Relay 357 'locks over its inner left front contact, to

battery at the normal contact of relay 356 and opens the circuit of relay 353. When relay 353 closes its back contact, a circuit is again y, closed through tone coil 365, this time oyer the right front contact of relay 357, left contact et relay 358, lower Winding of repeating coil 359, to ground and a second tone is transmitted to the A opera tor.

The release of relay 353, with relay oit relay 353 disconnects relay operated, closes a circuit freni battery Vover the right normal cont-act .of relay 358, outer left front .Contact .ot relay 35'?, Winding of relay 356 to ground Vat the left contact ott relay 355. Relay 350 `closes a locking circuit for itself over its lett alternate contact and connects the talking conductors 515 and 514 through to the B operato1"s headset. Relay 356 is slon'to.-(ipeiate and does not cut ol'lj the tone until a'ttcr a measin'ed in` teryal. The slow release and slonY operating` character oit relays 350, 3.5"? and ST8 serres the purliiose oi2 measuring the len .ot the tone and the interval bet-Ween toni. As soon as the second tone ceases the 14" operator the number of the wanted subscriber to the B operator and then disconnects her headset from the cord 1.03.

Oonaeotzlo/n of posit/0n to Sender.

rllhebperation of rel-ay 410 following thc. selection of anidle sender, as previously described, completes a circuit from battery through the Winding' Vet relay 151 in the first selector, inner left back contact .of relay 152, conductor 153, through the trunk finder. next to the uppermost front contact ot re lay 213, .conductor 234`r middle right .Contact xot relay 410, conductor 421, through the sender selector lto conductor 425, Winchne` ot' relay 881, outer right back cont-act ol" relay 809, .in parallel with the Contact et' interrupter 823, inner right back contact ot relay 825, .conductor ,420, through the sender selector', conductor 422 inner right tron'.r contact et relay 410, inner right trent contact ot' relay .401, conductor 23?, uppern'losl Contact ot' relay 21?, through the trunk iindcr, conductor 154, .outer lett back contact ot' relay 152, lett ufindinp; ot relay 151. Contact 155 to ground. Relays 151 and 881 operate in this circuit, relay 151 closing:v a circuit Yfrein battery through the Winding' oit relay 150, trent contact o1: relay 151 to ground at the bach Contact et rela-i152. No further operation or" the vfirst selector occurs at this tinie. Y

The operation of rela-y 881 prepares the sender to register the .wanted number and closes lan obvious circuit for relay 882. Relay 882 in. turn operates and 4closes .an obvious circuit tor relay 803. Relay 808 in operating connects battery over its left front .eontact to the register' relays, and 4connects ground A.over its right front contact and. the bach contact otrelay 809, toconductor 610, to coni-plete :the holding circuits .of vcertain relays as will hereinafter appear. It also closes an obvious circuit for operating relay Relay 307 connects ground over its right tron-t cenitaet and the left vcontact 0f .ker 80.5 te test .lee-d 415 Awelkies the sender busy. lt also closes an obvious cireuit for relay 802 which clisconneetsground from conductor 416 and disconnects battery v30.0 to grounded conductor Winding of relay 883.

As ,soon as relay 803 operates, connecting ground to conductor 610, relay l600 operates v in a circuit from battery through its Winding, outer left back contact of relays 603 004, G05, 60.6 and 608, conductor V609 to grounded conductor 610. lWith relay 600 operated, a circuit is closed to indicate to the position thatthe sender is ready to register the number of the `Wanted subscriber. This circuit may be traced frein battery over the lett front contact oft relay 803, .conductor G12, through the right Winding .of relay G13, outer right front contact .of relay `600, .conductor 620, Winding of relay 8,84, conductor 42.4, sender selector brush .429, conductor 461, inner left front contact of relay 517, position selector brush ,558, .conductor 522, outer left back contact of relay 305, Winding of relay 30.4, conductor 315, right back `contact of relay 316, normal contact of relay 81S to ground at the right :front Contact of relay 314.

Relay 304 operates in this ,circuit but relays 613 and S84 do not. Relay 304 closes a circuit from grounded conductor 315 over .its front contact, left hack .contact of relay 31.9, Winding of relay 30:6 to battery. lie-- lay 30.6 operates and locks over its inner left 4Contact to grounded 4coinluctor 315. rl`he .operation of relay 306 ,extends conductor 506 to the numerical keys. lt alsol .closes a .circuit frein battery through .the Winding` ,of relay 30,5. iniddleleft contact ot relay 31,5. In eaddition it opens the circuit ot the White lamp `303 indicating,- tothe TB operator ,that the sender is ready to receive registrations. The .operation of relay .305 extends conductors 521 and through to the numerical keys. It .may `be noted that conductors 522 and 521 are extended through resistance coils so as to compensa-te for the connection of rolay 555 iin series with conductor 506. The voperation of relay 305 opens the circuit ol relay 20.4 and that relay releases. i

Registration 0f called auf/uber.

.llVhen the B operator observes that lamp 303 has been extinguished she will operate the keys .of her leyset in accordance .With the number given her by the A operator. The operation 4of .each key .connects direct ground or ground through a resistance such Vas resistance 321 or 322`toconductolrs 506, ,521 and in a combination determined by ,the lrey pressed. Following is a table inl..- cating' the relationship between the keys of the f B operatons key set, the conductor to wwhich gr/freund is applied and the nature of that ground (whether direct or through are- Sislesel, and elle relay 01' relays .Operated thereby in the first register of thesender.

The relays of the various `sender registers are similarly located, socthat the correspondence between a key andthe proper relays ofV other registers may easily be determined from the drawings.

Key. Conductor` Resistance.

521 None 500 321 521 None. 521 None. A 500 None.

521 322 506 None.

521 322 506 321 500 321 522 None.

522 None 506 None 522 None 506 Nene In the case of keys 4t and 5 the connection of ground to conductor 521 through resistance 822 serves to bringe-bout the tranc- 'er from one register to the next-i as Will be pointed out hereinafter. y

Should the B operator press one or more of the numerical keys before the lamp 808 `is extinguished (which indicates that the sender has ,not yet been attached, at which time relay 805 is not operated), relay 864e will operate in a circuit which may be traced `from grounded battery over the inner lett or outer right back contact ot relay 805, through retardation coil 860 or 361 over the back contact or" relay 862 or 868 over the contact of one or more of the numerical keys, through thewyinding ofrelay 36e to ground at the right front contact ot relay 314. Relay 864'( operated closes a circuit tor, relay 319 `through its Winding- `over the 'liront contact of relay 864, lett back contact oli relay 816 to ground at the right front contacto't relay 814. Relay 819 locksovervits llett front contact to its energizing circuit independent ot relay 864 andcloees a` circuit ttor lamp 308 over its right front contact, to ground through interruptor 841. 7h-en the sender is attached the sender indicator lamp 808 will be extinguished as explained hereinabove. r y, i

`Relay- 808, when operated as previously described, closes a circuit extending from battery, through thewinding of relay ,818, lett baclrcontact oi' relay 826, conductor 83e, to grounded conductor 610. Relay 813 operates and closes an vobvious circuit for relay 814e.- Y

Assuming,` that the Wanted number is 2608 the-13?Y operator Will lirst press numerical key 2 representimg,- the first digit ot the .ati the right trent contact called number, whereupon relays 888 and 613 Will operate in series in a circuit Which may be traced from battery, conductor 612, through the right Winding oit relay 618, outer right front contact oi" relay 600, conductor 620, Win-ding,l orel-ay 888, right front contact of relay 802, conductor 4118, contact- .and brush l2/Z of the sender selector, conductor 419, inner right l'ront Contact of relay 517, conductor 554, brush and contact 558 ot the position selector, to conductor 521, and thence over the'inner left :front contact ot relay 805, retardation coil 861., back contact ot' relay 862, through the right closed contact ol operated key 2, conductor 825, right front contact oi relay 805, to ground of relay 814e. Since direct groundis connected to the circuit o relay 618 by key 2, as described, relay 613 will operate and lock in a circuit from battery over the inner right back contact of relay 809, conductor 632, inner right front contact of relay 600, left Winding' and inner left 'liront contact of relay 618 to ground. Relay 888 operated, operates relay 614 in acircuit which may be traced from battery through the Winding' of relay 614, outerlett front contact of relay 600, conductor 621 to ground at the outer ri ght front contact of relay 888. Relay 614 operated, locks over its inner right contact, Winding ot relay 608, conductor n609 and grounded conductor 610. Relay 603 does not operate, being shunted by the operating circuit for relay 611i. Relay 611i also closes a circuit for operating relays 619, 812 and 816. This circuitmay be traCed'rOm battery over the right backy contact oit relay 826, lett Winding' or' relay 812I7 inner lett back Contact of relay 817, conductor 622, l-e'ftvfront.y contact of relay 614e, conductor A62,8, right back contact ot relay 62,5, right front Contact ot relay 618, Winding of relay 619, conductor 626, through the4 Winding` of relay 816, outer left back Contact of relay 818, conductor 885, .trent contact of relay A811i, to ,aground over conductor 884. Relay 812 locks in a circuit from battery rat the right back contact of relay 826right Winding` and inner right arma! ture oit relay 812to grounded conductor 884. Relays 619, 812`and 816 are employed in .establishing the connection and will be discussed hereinafter.

lNhen numerical key 2 is released by the l operator, relay @Separates in the locking circuit-.oit relay 611i since the release el" key 2 permits relay 888 to The operation of relay 603 opens the energizing circuit for relay 600 whereupon'relay 600 releases. Relay 608 oneratedvoperates relay 700 in a circuit which may be traced from battery through the Winding ot relay 700, conductor 627, router lett front contact of relay 608, outer lett baclrcontacts etv relays 6.04, 605, 606 and 608 to grounded 614 operated the locking circuit ot relay 613 entends from ground over the inner lett front Contact and lett Winding' ofreay 613, outer right 'front contact ot relay 61st to battery over conductor 632 maintaining?,l the locking circuit after relay 600 releases.

lVhcn numerical hey 6 is depressed represent/ingl the second digit` ot the called number, relay 712 Will energizein. a circuit Which may be traced trom battery over conductor 612, through the right windings otl relays 770 and 712, inner right contact of relay 700. contact or relay 423 ot the sender selectori conductor 420, through the Winding oit relay 555, outer rightitront contact of relay 517 through brush and contact 556 ot the position selector to conductor 506. and thence, over the right front contact of relay 306, conductor 328, through the contact oct operatedl lzey 6, conductor-.320, through resistance 321, to ground on a conductor 325. Relay 770 does not operate in the circuit due to the presence ot resistance 321 in the circuit. Relay 712 locks in a circuit troni batt ery on conductor 632, through the inner lett front contact ot' relay 700, lett Winding and inner left front Contact ot relay 712 to ground.

The operation of key 6 also closes a circuit 'troni grounded conductor325 over the right contact ot key 6, back Contact of relay 363, through retardation coil 360, vouter lett front contact ot relay 305, conductor 522, brush 553 of the position selector, inner left front cil-utact ot relay 517? conductor 461. brush 4229 oi" the sender selector, conductor 424i, winding ol relay 364, conductor 620, outer right iront Contact oit relay 700, right Windingl of relay 711 to battery over conductor 612, Relays 88a and 711 Aboth operate. Relay 711 locks in a circuit `from battery on conductor 632, inner left front cont-act or relay 700, left Winding and inner left front Contact .ot relay 711 to ground. Relay 834i closes a. circuit from battery on conductor 632, over the inner left 4front Contact ot relay 700, Winding of relay 701, conductor 707, middle lett front Contact ot relay 700,` conductor 628, outer right trent contact ot relay 88e to ground. Relay 701 loclrs vover its lett front Contact to ground. Relay 384 in operating also closes a circuit from battery through the Winding of relay 615,'conductor 629, outer le-l'lt front contact et `relay 700, inner right trent contact of relay 884 to ground. Relay 615 locks in acircuit over its right Contact, Winding ont relay 604,150 grounded conductor 600. Bela-y 604 does not operate in this circuit being shunted by the operating ground -for vrelay 615.

606, conductor 423, brush- When numerical key 6 is released by the operator relay 604i: Operates in Aseries with relay 615. The operation of relay 604 opens the energizing circuit for relay 700 at its outer lett back 'contact yujhereu'pon relay 700 releases. Relay 6011 operated also closes an enerizing circuit for relay 702 which may be traced from battery through the Winding ot relay 702, conductor 630, outer left front contact ot relayy 604i, through the outer lett baclr contacts ot relays 605, 60.6 and 608 to grounded conductor 609. The operation ot relay 702 places the sender circuit in position to receive registration upon the thirdy set of register relays.

vWhen the numerical lrey 0 is pressed by the B operator ground will be connected to conductor 506 through resistance 321 Vand to conductor 322 through resistance 322. The circuit of conductor 506 is extended as previously traced to conductor 631 and thence over the inner right frontcontact of relay 702 to batterythrough the right windings ot relays V772 and 703. Relay 772 operates but relay 703 cannot operate in series With resistance 321. Relay 722 locks in a similar' circuit. to that ot relay 613. Relay 884 opcrates in the circuit of conductor 522 which entends as previously traced through the Winding of relay 834 to the outer right conf tact of relay 702 and through the right Winding of relay 771 to battery on conductor 612. Relay 771 will not operate in this circuit due to the series resistance 322.

Relay 884 closes an operating circuit for relay 719 similar to that traced for relay 701. Relay 719 locks over its left armature to ground. Relay 616 operates in a circuit similar to that Jfor relay 615 and locks through the Winding ot relay 605, to grounded conductor 609.

When the B operator releases numerical key 0, relay 605 operates in series With relay 616. The operation oit relay 605 opens the energizing circuit of relay 7 O2and causes relay 705 to operate in a circuit over a front contact of' relay 605, and back contacts ot relays 606 and :608 similar toxthat traced for relays 700 and 702. The operation of relay 705 places the sender circuit in position to receive registration lon the fourth set ot register relays.

When the numerical lrey 3 representing the fourth and last digit ot the called number is pressed by the B operator, relays 773 and 7 operate in series in a circuit eX- tending to kconductor 506, and through the contact of .operated numerical `A`lreyA 3,` to ground. RelaysV 773'and 774` lock in similar circuits to the locking circuit of relay 613.

A circuit is also closed trom battery on conductor 6127 through the right Winding of relay 775, and the Winding of relay 883, to conductor 521, and the right closed contact of numerical key 3 directly to ground over `conductor 325. Relays 775and `883 both operate in this circuit, relay 775 lockingl to ground over its inner left front Contact.

Relay 617 operates over the contact ot relayV 883 and locks through the winding of relay 606 t-o grounded conductor 600. Y

`When `numerical key 3 is released the B operator, relay 606 operates in series with i'elay 617, opening the circuit of relay 705 whereupon relay 705 releases. rlllie operation ot relay `606 closes a circuit tor operating` relay 608 which may be traced from battery, inner lett frontl contact of relay 606, left back contact ot relay 607 through the Winding of relayV 608 to grounded conductor 609. The operationpof relay 608 `connects ground to conductor 423 over its inner right front contact and disconnects the B yoperator `troni the linl; circuit as Will be hereinafter described.

As'lias been explaineththe setting `up o't the first'digit by the B operator, operates one of the relays 670, 619, 671, 672 or 673. These relays operate individually when the `register relays 613, 625 and 624 are operated .in different combinations and either alone or in cooperation with the register relay 646 are effective to operate the relay 607 to indicate that aV five digit number is to be recorded. For example, it' the {ii-st digit registered is either two or seven, relay619 is operated. It the digit is tivo, and it is desired to record five digits ttor connections to all substations designated by numbers Whose first digit is tivo, then the right armature of relay 619 is connected to conductor 610 Jfor operating relay 607 and all the other armatures of this group of relaysivould remain unconnected. It, however, the digit seven indicates the tive digit group, the lett armature ot relay 610 is connected .to conductor 610 and since, 'for recording the digit seven, relay 646 is also operated, the circuit of relay 607 ivill be prepared. Thusthe right armatures of relays 619,' 671.v 672, 673, and 670, if connected, will causo the operation of relay 607, it the lirst digit recorded is either tivo, three, tour, live or sift iespectively, and the lett armatures ot relays 610, 671 and 672. it connected, will Cause the operation of relay 607, it the first digit recorded is either seven, eight or nine, respectively. In the drawing', it `will be noted that the lett armature only oi relay 672 is shown connected and thus a live digit number is recorded only when the .[irst digit recorded is nine.

The operation registration ot the second digit closes a circuit for relay 824 which may be traced from battery through windingl of relay 824, Vouter right bacltcontact ot relay outer lett back contact ot relay 821. lett front contact ot relay 812, conductor 644, inner lett -front contacts of relays 603 and 604, con-V otrelay 604 following` they Which in ay ductor 643, contact .of interrupter 822 to ground. Relay 824 operated, closes an operating pathV for` relay 825 and a` locking path `tor itself Which may be traced from battery relays 824 and 825 in series, right front contact or' relay 824 over the inner lett back contact o't' relay 821 to grounded conductor 610. Relay825 operated, removes the shunt which has been closed until this time around interruptor 823. Interrupters 823 and 822 are mechanically related so that the contact of interrupter 823 opens at the same time that interrupter 822 closes its contact. The operation of relays 824 and 825 thus insures against part of a pulse being sent out to the step-by-step switches over the leads 425 and 426. The removal oit the shunt by the ,operation of relay 825 prepares tor the operation Vofthe sivitches'inaccordance with inter ruptions controlled by thecounting relays.

The' circuit for operating iirst selector 150 ldivas completed when relay 410 operated and was traced from battery, through the right ivindine'ot relay 151, thence over the contactot interrupter 823, andthe inner right back contact of relay 825 `in "parallel, and back to the lett Windingof relay 151,fand ground at contact otrelay 155 at the first selector. f The operation of relay 825 as above described leaves this circuit dependent on the contact of interrupter 823. The

`operation of relay 156 under the control of relay 151 as previously described prepares an operating' circuity tor vertical magnet 157, which may be traced from batterythrou'gh the Winding of' magnet V157, winding' of relay 158. inner front contactuot relayv 156, to the back contact of .relay 151, which circuit is completed when relay151`releases on the first opening oli' the contact of interrupter 823. A

The number of interruptions of thepulsing' circuit is controlled by the operation of the counting' relays ot Fig. 8 asivill hereinafter appear. ln lregisteriirtrthedigit2, as the tirst digit of the Wanted nuinbei,relay 613 was operated and locked in turn oper ating` relays 816 and 812 as above described.

As soon as relay 604 operates, indicatingV the completed registration ot the' second digit,

-relay 819 operates in a circuit which may beV traced from nrounded battery throughthc ivindingoi relay 8.19, inner. lett front contact ot relay 816, inner lettback contact of relay 818. outer right contact oirelay 825,

outer left bacltcontact 821,'right 'front contact 'ot relay812, conductor 644. inner left front contacts of relays 604 and 603, conductor 643, contact of interruptor` 822 toV ground. Relay 819 operated,'closes a locking' circuit tor itself in seri-es with relay 818 the `winding` of relay819, front" Contact oft relay 819, Winding of, relay 818, outer lett through the windings of be traced `from battery through isc ' Y interrupter 822,

conductor 885, grounded conbacl; contact ot relay 817, lront contact of relay 8111 to duc-tor 834. lfhen interrupter 822 opens its Vcontact relay 818 operates in this circuit and opens the venergizing circuit `for relays `e316 which releases. Relay S12 does not release at Vthis time as it is locked through its rlght V Winding and inner right 'front Contact to battery, through the Winding ofy relay 820,

right vback cont-act ot relay 82T, inner left front contact o'l rel-ay 818, outer rightV front contact of ,relay `825, and thence asV traced for relay S19 Ato the closed contact Voli interrupter S22. Relay 820 operated, locks in a circuit 'from battery through the Winding and trout contact ofrelay 820, Winding ol' relay821 to grounded conductor 885. lielay S21 operated, releases relays-S24 and 825 by opening its inner left back contact. The release of'ielay 825 Will reclose the shunt around interrupter823 and thusprevent the further interruption of the circuit of relay 151.

At the first opening of the Contact of interrupter 823, relay 151 releases completing the circuit above traced ior magnet 157, advancing the lirst Vselector one vertical step. The second interruption of the circ-uit of relay 151 by -interrupter 823 causes the advance of the first selector in a second vert-ical step. Relay 156 operates in the circuit of magnet 157 and, being slow to release, mains operated as long as the circuit ol" relay 151 is being n'iterrupted. T he operation or" relay 156 closes la circuit from battery through the Winding of relay 159, oil-normal contact 160, front cont-act oil relay 158, outer front contact of relay 156 to ground. Relay 159 locks in a circuit from battery through its Winding, ofl-normal Contact 160, back contact o't'rotary vmagnet 161, right front 'contact of relay 159, inner lett back contact of relay 152 to ground'. lVhen the release ol relay 625 closesthe shunt around interrupt-er 823, relay 151 remains operated long enough to permit relay 158to release.V rllhe release or' relay 158 closes a circuit from battery, through the Winding of rotary magnet 161, left Vfront cont-act of relay 159,`nornial contact of relay 158, outer front cont-act of relay 156 to ground. Magnet 161 operates, releasing relay 159 and advancing the switch one rotary step into engagement With the .first outgoing trunk. It this trunk is busy, ground v-:ill appear on the sleeve terminal enga ed by brush 162. As soon as magnet '161 c oses its back contact relay 159 will -be Y d uctor 8311-.

reopera-ted in a circuit extending through its Winding', olli-normal Contact 160, back contact of magnet 161, right back Contact ol relay 152, sleeve brush 162 to ground. The. operation of relay 159 Will reelose the operating circuit for rotary magnet 161 and the switch Will take another rotary step. As long as sleeve brush 162 encounters ground, relay 159 Will be reoperated after each rotary step and the switch advanced. A second circuit for relay 159 also exists which may be traced through its Winding, oil-normal contact 160, back contact of magnetl 161, Winding ot relay 152, contact 163 to ground at the outer i''ront contact of relay 156. As long as sleeve brush 162 encounters ground, relay 152 is shunted and does not operate. As soon as an idle t-runl is `found, characterized by the absence otground, rela-y 152 op crates. Relay 159 being marginal does not operate in this circuit. The operation of relay 152- extends the tip, ring and sleeve conductors through to the nextselector. 1t

also opens the circuit of line relay 151 which relay releases in turn releasing relay 156. However, relay 156 holds its armatures attracted for a time, thus maintaining ground on the sleeve conductor until the line relay and corresponding sloW-to-release relay ot the next selec-tor have operated to render both selectors busy. Y

The ground over sleeve brush 162 completes a locking circuit :tor relay 152 which may be traced from battery, through the Winding or' relay 159, oil-normal contact 160, bach contact of magnet 161, Winding oft relay 152, contact 163 front contacto'li relay 152, brush 162 to ground.

The operation of relay S21, as previously described, 4closes the circuit ot relay 626 which may be traced from battery. through the Winding ol' thatrelay over the inner lett liront Contact oit relay 821 to grounded coucircuit :tor relay 813 at its left bach: co1. Relay 813 in turn releases relay 611. ll 826 also removes battery from the en gi ing circuit ol relay 812'u'hich releases. The release of relay'Sll, releaseel counti C 'elays 818 and 819, 820 and S21. Relays 663 and 614 release due to the operation ot relay 826 which pla-ces battery on conductor 6l() shunting these relays. The release ol relay 821 ope-ns the energizing circui ttor relay 826 at its left front contact. Relay 615i leases When relay 614..- releaees due to opening of the locking circuit oil: the lat lr relay at the outer right front contact ot relay 6141-. At the close of any digit, therefore, .the operation ot relay 626 releases the various registerv relays, and relays 612 and Slet are release-d and again operated to provide an interval for the purpose of allowing time yfor the switches to trunk hunt. lllhen relay 826 releases, relay 818 operates aga-in in the Relay 826 opens-the energizing circuit previously traced. Relay 814 will accordingly reoperate.

lay 817, conductor 654, through the right front contact of relay 7 O1. conductor 645 to `the outer right loaclt` contact of i ground at relay 603. The operation of relay 827, whenever the digit is greater than 5,.alters the sequence of the counting relays to cause their -repeated operations to count incre than tive interruptions of the switch control circuit.

ine counting for sending out `the seconddigit (t3) will `start at counting relay 818 which operates in a circuit which'inay loe traced from ground on conductor 834, .front contact of relay 814, conductor 885, outer left hack contact of relay 817, through the 647. out er right front winding of relay 818, conductor right hack contact of relay 70, y Contact of relay 711, outer left -frontcontact of relay712, conductorv 648,7outer left front Contact of relay 615, right hack contactof relay 614, conductor 622, inner left hack contact of relay 817, relay 812, to battery at the right hack contact of relay 826. Upon the closure of the contact of interrupter 822 with relay 8,18operated, an energizing circuit is closed for relay 828. "it the same time the firstk opening of interrupter contact 823 causes the second selecto-r (not shown)` to take a` vertical step.V rllhe energizing circuit for relay 828 inay be traced from battery, through `the winding of that relay, inner right front `contactof relay 827, inner leftfront contact of relay 818, `outer=right front contact of operated relay 825 over the circuit previously traced tothe closed contact of interruptor Relay 828 operated will `lool; through itsA Y left fro-nt Contact in series with the winding of relay 817, outer ri ghtfront contact of relay 812 to groundedconductor 834. 817 will operate in this circuit when interrupter 822 opens its contact and opens the' energizing circuit for relay 827 at its right haelt Contact, whereupon relay 827 releases; rl`he operation of relay 817 also opens the r818 which re leases. Relay 829. then operates in a circuit -uhich may be traced from battery, through the winding of Vthat relay, left haelt contact of relay 835-). inner left hack contacts of relays 830, 816 and 818, outer right trent contact ofrelay825 and thence tothe closed contact of interrupter822. 'Thus the second of the sixpulses ofthe second digit willloe counted. 1^ :L f

Relay 829 operated, locks through its left Relay 827 therefore energized as haelt contact :of .-re-

left winding Y of e Relay `fronteontact in series with the winding of `relay829 in a circuit similar to that traced for' relay 819, relay 839.0peratin'g wheniinterrupter 822 reinovesthe operating ground froln relay 829. Upon the third closure of* interrupter 822 with relay 839 operated, counting relay 832'will operate in circuit similar to that traced for counting relay 819. This will complete the counting of the third pulse to the second selector. e

Relay 832 operated, will close a locking circuit forxitself through itsleft front contact inl series with the Winding of relay 830,

which latter relay operates. The operation of relay 830 will open the energazingl *circuiti for relay 839 and the locking circuit for relay 829, whereupon `these two relays release. Theoperation ofrelay 830closes an renergizing path for relay 883 at its inner left front contact and relay 833 operates upon the fourth closure of the contact of interrupte'r 822, counting the fourth pulse of the second digit 6.

Relay 833 operated will close a locking circuit for itself through its left front oon-' tact inseries with relay 816 which relay operates. The operation of relay 816 will open the energizing circuit of relay`830and the `locking `circuit for relay 832, whereupon "closure of the contact of interrupter 822, relay 819 will operate 'count-ing the fifth pulse to the switch. 1 Y 1 Relay 819 operated, will-close `a locking path for itself through'its front contact in wliich prevents the further interruption of the switch control circuit. The operation lthese two relays will release. 'Upon the fifthL i placesthe shunt around interrupter 823f ofv relay`821 operates relay 826, the operal tion of which releases 4relays 818 and 814. `Relays 615 and 664 will also release. r

The thirddigit zerowill he inarlted on V,the countingrelays to determine at which `point vthe operation of the counting relays will beginr in a mannersiinilar to that described for the'second digit.' Relay 827 will at first/be operated (the third digit also heing a nurnloer valo'oye 5) whereupon the following pairs of counting relays will loe operated to count 10 pulses: 829-839- y 830, 833-816, 8194-818, 828-817, 829-839 (operated for' the second time), 832-830,

833-.8l6, S1.9-S1S, 820-821- At'the close o'f-the digit the operation of relay `821 cau-ses sending to ceasey by the operation ot relay 826. The various register relays are caused to release as described. f

The fourth digit 3 Will be marked on the .counting relays, the operationot' the countlVhen the B operator releases. the key corresponding to the last d1git of the nuinber received from the A operator, and rele'y 608 operates as previously described a circuit is closed from battery through the Y Winding of relay 335, back contact of relay 362, conductor 328, right tront contact ot' relay 306, conductor 506, brush and contact 556 ot the position selector, outer right front contactotrelay 51'?, Winding of relay 555.

- conductor 420, lbrush and contact 428 of the f circuit of relay sender selector, conductor 423,V inner right front contact of relay 608 to ground. The current now tlowing in this circuit permits relay 555 to operate in turn operating relay 549.

Y Relay 549 operated, `opens at its outer left back contact, the energizing circuit 'tor relay 549l starting the release ot the position. Relay 549 opcrated,ialso operates relay 406 in a circuit which may be. traced from battery,

' through the winding of relay 406, inner leit front contact of relay 549, conductorsv 559, 545, 408 and 412 .to ground at the middle front contact oit relay 403. Relay 406 oper-` ated, locks through its inner right rontvcontact to conductor .V403 and closes a shunt around the `Winding, ot' relay 517',v which eircuit may be traced from battery through the Winding o'l' relay=511,` outer right front contact ot' relay 406, right back contact of relay 549. to grounded conductor Y40S. This circuit holds 'relay 511 operated and releases relay 517. The release of relay 517 opens the conductors connecting the sender and the position. Relay 406 in i operating removes ground trom-'the test brushr527 ot' 'the position selector. It also opens the` energizing 510, whereupon relay 51'0 releases to disconnect the position from the conductors incoming from the A operator. Relay 406 also closes a holding circuit for relay 555 atits outermost left front contact.

i In addition relay 406 opens the holding circuit of relay 202, but relay 549 has already closed a substitute holding circuit over its outer right front contact. The. `operation of relay 549 also opens the circuit of relay 300 so .thatV relay releases in turn releasing relay 301.

The release of relay 301 closes a circuit from battery through 4lamp y3,02, inner right front contact of relay 35.4, outer right back contact of relay 301, yinterrupter 341 to ground. Lampl 302 iiashcs in this ycircuit until the operation ot' relay 406 removes ground from conductor 507. The removal ot ground from conductor 507I permits the release of relay 314 which removes ground from -conductor 325.; opensthe locking circuit ot' relays 306 and 319;v opens the holding circuit otrelay 305; and opens the energizing circuit of relay 354. Relay 354 in turn releases relay 353 Which opensthe circuit of relay 355 and in turn the circuit ot' relay 356. The B operators position is now free to care lor calls incoming on other link circuits.

lt Will be clear from the foregoing description that as soon as they operator has finished setting up a number the sender will indicate to the link that the operation of the position has been completed and Will bring about the disconnection of thelink from the position atter which the position is free to be seized `by another link.

Release of the senden Then the sender finishes controlling the establishment ol" the connection, relay 608 releases, opening the` circuit of relay 555, Which releases in turn and opens t-he energizing circuit for relay 549.l Relay 549 releasing, connects ground from conductor 408, inner right front contact of relay 406, over the inner left back Contact of'relay 549, conductor .430, and the front contact of relay 431 to cutthrough conductor 238 of thetrunk. The release oft' relay 549 noW opens the holding circuit oi relay 202 and that relay releases disconnecting ground from conductorx236 and releasing relay 403A.A The release of relay 403 opens the locking circuit Jfor relay 406 and the holding circuit of relay 511. The release of relay 202 also opensr the circuit of relay V213 which in turn opens the pulsing leads connecting the sender and the switches. The opening of these conductors permits relay 881 to release. Relay 882 is thereupon released in turn releasing relay 803.` The release of relay 803 removes battery and ground from the control conductors of the sender and in turn releases relay 807. Relay 807 releases relay 802and the sender is noW'in condition to serve another call.

Unt through of connection.V

238 as abovedescribed completes a .circuit 

